Electric plug with insulation piercing contacts



J. C. PUIG Aug. 13, 1968 ELECTRIC PLUG WITH INSULATION PIERCING CONTACTS Filed July 5, 1966 INVENTOR.

JWM/ 0044A P016- W M Haw,

United States Patent 3,397,380 ELECTRIC PLUG WITH INSULATION PIERCING CONTACTS Juan Coma Puig, Carretera de Caldas 118, Granollers, Barcelona, Spain Filed July 5, 1966, Ser. No. 562,610 Claims priority, application Spain, Sept. 27, 1965, 318,221 4 Claims. (Cl. 339-99) ABSTRACT OF THE DISCLOSURE An electric plug capable of making electrical connections between contacts of the plug and conductors to which the plug is connected. The plug contacts are carried by a plug housing and are engaged by electrically conductive blades extending into the housing and defining between themselves a space which is adapted to receive a spreader means which spreads the blades apart from each other toward a pair of conductors, respectively, which also extend into the housing. The blades carry tooth members which pierce through the insulation of the conductors and a spring means in one embodiment urges the conductors respectively toward the blades and in another embodiment urges the blades toward the conductors.

The present invention relates to electric plugs.

In particular, the present invention relates to that type of electric plug which has a pair of electrical contacts, either in the form of a pair of prongs or in the form of a pair of conductive sleeves for receiving prongs, so that the electric plug can provide an electrical connection.

As is well known, it is required with plugs of this type to be able to connect the electric contacts thereof respectively with a pair of electrical conductors. These conductors take the form of electrically conductive wires covered with suitable insulation, and according to the customary practice it is necessary to disassemble the plug, to strip the insulation from the ends of the wires of the conductors, to join the stripped wire ends to the plug, and then to reassemble the plug.

It has already been proposed to avoid the above complications by providing plugs which receive the electrical conductors with the insulation thereon and which are assembled in such a way that the required electrical connections are made between the contact elements of the plug and the conductors. However, the known constructions provided for this purpose suffer from several drawbacks. In the first place the electrical connections between the contact elements and the conductors are not always achieved. Furthermore, even where a proper electrical connection is made between the conductors and the contacts, the conductors are not securely retained within the plug so that one or more of the conductors are easily pulled out of the latter. Furthermore, the known plugs are not tightly closed so that foreign matter can have access to the interior thereof. In addition, with many known types of plugs of this type special tools are required for making the assembly.

It is accordingly a primary object of the present invention to provide an electric plug of the above general type which will avoid the above drawbacks.

In particular, it is an object of the present invention to provide an electric plug which will guarantee proper electrical connection between the pair of conductors, on the one hand, and the contact elements of the plug, on the other hand, respectively.

Furthermore, it is an object of the present invention to provide a construction where the conductors will be reliably positioned within the plug so that their proper engagement with the electrical structure within the plug is assured.

In addition, it is an object of the invention to provide a construction where the conductors are reliably held within the plug in such a manner that they cannot be pulled therefrom.

Also, it is an object of the present invention to provide a plug of the above general type which requires absolutely no tools of any kind to be used in the assembly of the plug with a pair of conductors.

In addition, it is an object of the present invention to provide a plug which in its fully assembled condition where its contact elements are electrically connected with a pair of conductors, respectively, will be tightly closed so that the interior of the plug of the invention is protected from the outer atmosphere.

Primarily, the electric plug of the present invention includes a hollow housing which carries a pair of contact elements which may take the form either of a pair of electrically conductive prongs to be received in a suitable receptacle or the form of a pair of electrically conductive tubes, for example, so as to receive a pair of prongs, respectively. A pair of electrically conductive blades engage the contact elements so as to be electrically connected therewith, and these blades extend from the contact elements into the interior of the housing where the blades, when they are in an unstressed condition, define between themselves a space of a predetermined magnitude. The plug housing is adapted to receive a pair of electrical con ductors respectively situated on opposite sides of the space between the blades, with the blades extending between the pair of conductors, and a spreader means of the invention is situated in the housing in the space between the blades, spreading them apart from each other. This spreader means has between the blades a cross sectional size greater than the above-mentioned predetermined magnitude of the space between the blades when they are unstressed, so that in this way the spreader means reliably spreads the pair of blades apart from each other, and as a result they will be displaced toward the pair of conductors. The pair of blades respectively carry a pair of toothed means which are directed away from the space between the blades so that the pair of toothed means are respectively displaced toward the conductors when the spreader means is situated in the space between the blades, and the pair of toothed means of the invention reliably pierce through the insulation of the conductors to press directly against the electrically conductive portions of the conductors which are surrounded by their insulation, so that in this way a reliable electrical connection is provided between the conductors and the contact elements, respectively.

The invention is illustrated by way of example in the accompanying drawings which form part of this application and in which:

FIG. 1 is a partly sectional exploded elevation of one possible embodiment of a plug according to the present invention, the left half of the structure of FIG. 1 being shown in section;

FIG. 2 is an exploded end elevtaion of the structure of FIG. 1 as seen from the left side of FIG. 1, with the left half of FIG. 2 also being shown in section, the sectional plane of FIG. 1 being taken substantially midway between the front and rear faces of the plug while the sectional plane of FIG. 2 is taken substantially midway between the ends of the plug;

FIG. 3 is an end elevation of the plug housing, showing the housing components spaced from each other with the left housing component of FIG. 3 being shown in section in a plane which is the same as the plane in which the section of FIG. 2 is taken; and

FIG. 4 is a sectional elevation of another embodiment of a plug according to the invention, FIG. 4 showing only the left half of the plug in partly assembled condition.

Referring now to the drawings, the plugof the invention includes a plug housing made up of a pair of substantially symmetrical bodies 1 and 2 which are composed of electrically non-conductive material, these bodies being symmetrical one with respect to the other as well as with respect to a central plane which extends between the longitudinal ends of the housing 1, 2. The bodies 1 and 2 when connected to each other to form the plug housing define a hollow interior space in which components of the plug of the invention are located, as described below. The walls of the bodies 1 and 2 are formed in the region of the upper ends of these bodies, as viewed in the drawings, with bores in which contact elements are mounted. Thus, the housing 1, 2 is formed at its upper end with threaded bores 6 which may be suitably countersunk at their upper ends, and these threaded bores 6 receive the electrical contact elements 4, respectively. These contact elements 4 are shown in the form of prongs which have threaded ends of reduced size extending threadedly into the threaded bores 6 of the housing 1, 2, but it is to be understood that the plug housing 1, 2 can be formed with bores for receiving electrically conductive tubular sleeves which form the contact elements of the plug and which are identically arranged with respect to the housing and adapted to re ceive prongs of another electrical plug.

In accordance with the invention a pair of blades 5, made of an electrically conductive material, respectively engage the contact elements 4 and extend therefrom into the hollow interior of the housing 1, 2. For this purpose the blades may be formed at their upper ends with suitable openings through which the threaded portions of reduced size of the prongs 4 extend, so that when the prongs 4 are connected with the housing the apertured ends of the blades 5 are clamped between the housing and the shoulders of the prongs 4 which are situated between their portions of large and small diameter, as shown at the upper left portion of FIG. 1. In this way the blades 5 are securely assembled with the remaining structure extending from the prongs 4 freely into the interior of the housing, and furthermore in this way a highly reliable electrical connection is formed between the blades 5 and the prongs 4. These blades may be made of a springy electrically conductive metal, so that they take the form of leaf springs, for example. In their unstressed condition the blades 5 define between themselves in the interior of the housing 1, 2 a space of a predetermined magnitude, and this space is of course of a tapered configuration due to the inclination of the blades 5. One of the blades 5 is shown in its unstressed condition in FIGS. 1 and 2.

A pair of insulated conductors 9 are adapted to be received in the interior of the plug housing 1, 2, and one of these conductors is also shown in FIGS. 1 and 2. The conductors 9 are respectively situated beyond the space between the blades 5 with the latter extending between the conductors 9 in the manner indicated in FIG. 1.

The plug of the invention includes a spreader means which has an elongated portion 12 adapted to extend into the space between the blades 5. This elongated portion 12 has a cross sectional area whose magnitude is greater than the magnitude of the space defined between the blades 5 when the latter are in their unstressed condition, so that as the spreader portion 12 is introduced into the space between the blades 5 these blades will be spread apart from each other and will thus approach the conductors 9, respectively. In the illustrated example the elongated portion 12 of the spreader means terminates in a convexly curved end which slides along those surfaces of the blades 5 which are directed toward each other, so that due to the inclination of the blades 5 with respect to each other and the size of the spreader portion 12 a wedging-type of action is achieved spreading the blades 5 apart from each other. The upper end of the housing 1, 2, as viewed in FIGS. 1 and 2, is open when the spreader means is not situated in the housing, so that the elongated portion 12 thereof can easily be introduced into the housing through the upper open end thereof.

In accordance with a further feature of the present invention, the pair of blades 5 respectively carry a pair of toothed means '8 for respectively piercing through the insulation of the conductors 9 to engage the electrically conductive interior portions thereof in response to spreading of the blades 5 apart from each other. The pair of toothed means 8 are respectively connected electrically with the pair of blades 5 and in accordance with the invention the pair of toothed means 8 include teeth which respectively extend along paths which differ substantially from the paths along which the conductors 9 respectively extend. These paths along which the toothed means -8 respectively extend across the paths along 'which the conductors 9 extend. In the illustrated example each toothed means 8 includes a portion 7 formed integrally with the blade 5 and extending obliquely with respect thereto. Thus, these portions 7 are bent laterally from the blades 5, respectively, having with respect to the blades 5 the oblique relationship indicated clearly in FIG. 2, so that as a result the teeth 8 situated at the free edges of the portions 7 which are directed away from the space between the blades 5 will necessarily extend across the conductors 9.

This feature of the invention according to which the pair of toothed means respectively extend along paths which differ substantially from the paths along which the conductors extend is of great advantage. While an oblique relationship as shown in the specific example is not absolutely essential, the teeth 8 should extend along a path which may be straight, curved, wavy, stepped, or any desired configuration so long as it differs substantially from the path along which the conductors extend. It has proved in practice that in those cases where the teeth extend substantially parallel to the conductors, especially where the conductors have a relatively small cross section, the teeth can extend into the insulation to become situated beside the conductive inner portions of the conductors without even engaging these conductive portions. Thus, by providing an arrangement where the teeth 8 extend along paths which differ substantially from those along which the conductors extend, the teeth 8 of the present invention cannot fail to be displaced into engagement with the conductive portions in the interiors of the conductors 9.

A further feature of the present invention resides in providing a springy, yieldable coaction between the conductors 9 and the toothed means 8. For this purpose the invention includes a spring means 11 in the form of a pair of leaf springs having the configuration shown for the left leaf spring 11 in FIG. 1. The housing 1, 2 is formed with suitable recesses in its interior for receiving the free ends of the leaf springs 11, in the manner shown in FIG. 1, and these leaf springs 11 engage those surfaces of the conductors 9 which are directed away from the blades 5 so as to yieldably resist displacement of the conductors 9 away from the blades 5 during insertion of the teeth 8 through the insulation of the conductors 9 into engagement with the inner conductive portions thereof. The size of the cross section of the elongated portion 12 of the spreader means together with the force and size of the springs 11 guarantee suflicient pressure to reliably cause the pair of toothed means 8 to pierce through the insulation of the conductors into engagement with the inner conductive portions thereof. In response to introduction of the portion 12 of the spreader means into the housing 1, 2 the electrical connection between the teeth 8 and the conductors is automatically brought about, in opposition to the springy force provided by the leaf springs 11.

A further feature of the present invention resides in providing the housing 1, 2 with a guide means for reliably guiding the pair of conductors 9 to locations where they will be properly situated with the pair of blades 5 extending between the conductors 9. For this purpose the end of the housing 1, 2 opposed to that end which receives the portion 12 of the spreader means is formed with an inlet opening 13 through which the conductors are introduced, and in the region of the inlet opening 13 of the housing 1, 2 the housing carries a deflector or guide member 14 which will deflect one conductor in one direction and one conductor in the opposite direction, so that in this way the pair of conductors are necessarily properly situated in the housing, as indicated for the left conductor 9 of FIG. 1.

The embodiment of the invention which is illustrated in FIG. 4 differs from the embodiment of FIGS. 1-3 primarily in that the spring means, which corresponds to the spring means 11, forms part of the spreader means itself. Thus, it will be noted that in the embodiment of FIG. 4 the spring means 11 and the recesses for receiving the same have been omitted. Instead, in this embodiment the portion 12 of the spreader means is modified so as to have a pair of elongated springy tongues 15 which act in the same way as the portion 12 but which in addition are capable of resiliently yielding so that they also function to yieldably urge the pair of blades 5, on the one hand, and the conductors 9, on the other hand, one toward the other. Thus, in the embodiment of FIG. 4 the conductors 9 are pressed against inner surfaces of the housing 1, 2, in the manner illustrated in FIG. 4.

Of course, the components 1 and 2 of the housing can be connected to each other in any suitable way as by suitable screws, by being pressed together, or by being cast in one piece, and such features do not in any way affect the invention.

According to a further feature of the invention the housing 1, 2, on the one hand, and the spreader means, on the other hand, are provided with a means for retaining the spreader means assembled with the housing. For this purpose the housing carries at its interior projections 17 over which projections 16 of the spreader means can snap so as to oppose withdrawal of the spreader means from the interior of the housing once it is introduced into the same. In this way accidental displacement of the spreader means from the interior of the housing is avoided.

In addition, the spreader means includes, not only the elongated portion 12, but an elongated transverse portion 18 which extends transversely across the elongated portion 12 and forms a cover for closing off the interior of the housing at its open upper end, as viewed in FIGS. 1 and 2. This transverse plate portion 18 of the spreader means is of the same contour as the upper end of the housing 1, 2 and it is formed with openings 19 through which the prongs 4 extend. When the parts are fully assembled the cover portion 18 of the spreader means tightly closes the open end of the housing so that the latter is reliably sealed off from the outer atmosphere with this construction.

It is apparent, therefore, that with the structure of the invention the electric plug presents a number of advantages. The plug of the invention is quite inexpensive and is in no way more expensive than a conventional plug. Furthermore, the construction of the invention is far simpler and more efficient than conventional structures, requiring no springs, pliers, or other tools for assembly of the components. In addition, the conductors are fixed in the plug housing in a highly reliable manner preventing withdrawal of the conductors from the plug housing even when pulling on the conductors with a force which would be sufficiently great to tear them.

The paths along which the teeth 8 extend with respect to those paths along which the conductors extend as well as the spring means, either formed by the springs 11 or the springy characteristics of the tongues 15, quarantee a reliable electrical connection between the conductors and the contact elements 4.

It is furthermore to be noted that the range of movement of the blades 5 by the spreader means of the invention together with the cooperation of the spring means enables the plug of the invention to receive conductors 9 of widely differing sizes with a reliable connection being provided irrespective of the particular diameter of the conductors.

What is claimed is:

1. An electrical plug comprising a hollow housing, a pair of contact elements carried by said housing, a pair of electrically conductive blades engaging said contact elements, respectively, and carried by said housing, said blades extending from said contact elements into the interior of said housing, and said blades defining between themselves, when they are unstressed, a space of predetermined magnitude, said housing being adapted to receive in its interior a pair of insulated conductors between which said blades extend so that said conductors are situated outwardly beyond the space defined between said blades, spreader means carried by said housing and extending into the interior thereof into said space between said blades, said spreader means having in said space a cross-sectional area greater than said magnitude of said space when said blades are unstressed so that said spreader means spreads said blades apart from each other toward the conductors, a pair of electrically conductive toothed means carried by and communicating electrically with said blades, respectively directed away from the space therebetween toward the conductors, and approaching and engaging the conductors when said blades are spread apart by said spreader means for piercing through the insulation of the conductors and engaging the conductive interior portions thereof in response to displacement of said blades apart from each other by said spreader means, said blades forming a pair of members and said conductors forming a pair of members and a spring means situated in said housing for urging one of said pair of members respectively toward the other.

2. The combination of claim 1 and wherein said spring means is in the form of a pair of leaf springs carried by said housing in the interior thereof and situated at the sides of said blades opposite from the space therebetween, said conductors being adapted to extend between said leaf springs and said blades.

3. The combination of claim 1 and wherein said spring means forms part of said spreader means.

4. The combination of claim 3 and wherein said spring means takes the form of a pair of elongated springy tongues forming part of said spreader means and engaging said blades not only for urging them apart from each other but also for yieldably urging them toward the conductors.

References Cited UNITED STATES PATENTS 2,810,894 10/1957 Kerr 33999 2,997,683 8/1961 Koenig 339-99 FOREIGN PATENTS 426,391 10/1947 Italy.

MARVIN A. CHAMPION, Primary Examiner.

J. H. MCGLYNN, Assistant Examiner. 

